1. Field of Invention
This invention relates to retaining wall in particular, to retaining walls constructed of prefabricated modular elements that support a natural or man-made slope.
2. Description of Prior Art
It is desirable in certain excavations to provide support for a natural or excavated slope to prevent its collapse. In practice, retaining walls are used to support, protect and stabilize slopes. Many factors enter into the engineering of a retaining wall based on the conditions of a particular slope, the load demands of the wall, and the wall's dimensions. In the past, retaining wall installation was time consuming and expensive. Prior art retaining walls begin with skeletal elements, usually made of metal, that are installed in the slope. Secondary operations are necessary to complete the wall, for example applying concrete surrounding the skeletal elements.
It is known in the art to create a wall using tiles having outwardly projecting flanges to improve the wall's resistance to rain, ice, snow and fire. U.S. Pat. No. 368,387 to Donaldson discloses a weather boarding or siding comprised of individual rectangular tiles having outwardly-projecting flanges or ledges arranged on opposite sides of the tile. The lower edge of the flange has a series of perforations and is secured to a frame of a house or other structure by nails or screws inserted through the perforations. The flange of an adjoining tile covers the flange having attaching means, concealing the fasteners from view.
The flange along the upper edge of the tile is beveled in one direction. The flange along the lower edge of the tile is beveled in the reverse direction. Thus when adjoining tiles are connected, the flanges overlap one another and the beveled edges form a dovetailed joint. This beveled flange arrangement is required to connect the adjoining edges of the tiles together and prevent the edges from displacing relative to each other.
However, this type of tile is not suitable for a retaining wall because the tile's construction is not self-supporting. Each tile is individually fastened to a frame. The edges do not abut each other, but merely overlap. The dovetailed joint between adjoining tiles is required to prevent mating edges from displacing. Without the dovetail, the tiles disclosed in Donaldson would slip and move.
As discussed above, each of the tiles disclosed in Donaldson must be secured to a frame. The tiles are not capable of standing on their own. The perforations for securing the tiles are located in the flanges on the tile's surface. The perforations on the tile's surface compromise the structural integrity of the tile.
U.S. Pat. No. 4,718,792 proposes prefabricated retaining wall elements that provide a process for facing and supporting slopes in a minimum number of operations. This prior art retaining wall is provided as a plurality of prefabricated elements having edges that are designed to connect to neighboring elements. The prefabricated elements are solid, and interconnect with each other, providing a stable support under load or against external forces.
A drawback to this type of prefabricated retaining wall element is that it is necessary to compromise the integrity of the element in order to anchor the element. The element is provided with an insert into which a mechanical extension device is inserted and fixes the panel to the earth underlying the retaining wall.
The insert is a reinforced area having a hole for the ground anchor. The reinforced hole is made directly into the panel. This hole in the flat panel disrupts the integrity of the panel which reduces the overall stability and strength of the entire retaining wall.
In any prior art retaining wall system it is necessary to use temporary bracing to hold the wall in place until the earth is backfilled. This is a time consuming and costly disadvantage that has yet to be overcome with a practical solution until the present invention.
There exists a need for a retaining wall system that will not require jeopardizing the integrity of the elements to anchor them to the earth. There is also a need for simplifying the construction of a retaining wall by eliminating the need for temporary bracing to hold the wall in place until it is completed. The present invention proposes an improved prefabricated cast concrete retaining wall element that overcomes the disadvantages discussed above relating to prior art retaining wall systems.